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1.
Shahriar Shahi Saeed Rahimi Hamid Reza Yavari Negin Ghasemi Fereshte Ahmadi 《Journal of endodontics》2018,44(10):1462-1466
Introduction
Previous studies have reported that it is difficult to obtain proper anesthesia in mandibular molars with symptomatic irreversible pulpitis, and supplemental injections are usually unavoidable. The aim of the present study was to determine the anesthetic efficacy of articaine in mandibular first molars with symptomatic irreversible pulpitis with 3 injection methods: an inferior alveolar nerve block (IANB), an IANB with an intraligamentary injection, and an IANB with buccal infiltration before initiating the endodontic treatment.Methods
Ninety-six patients (54 women and 42 men) with a diagnosis of symptomatic irreversible pulpitis in mandibular first molars were selected and randomly assigned into 3 groups (n = 32) according to the injection method as follows: group 1, a conventional IANB injection; group 2, an IANB injection, and after profound lip numbness after the IANB (after 15 minutes), buccal infiltration was administered; and group 3, an IANB injection, and after profound lip numbness after the IANB (after 15 minutes), an intraligamentary injection was performed, and after 20 minutes from the IANB, the endodontic treatment was initiated. The anesthetic solution was articaine 4% with 1:100,000 epinephrine. Success was defined as no or mild pain on the basis of the visual analog scale recording upon access cavity preparation or initial instrumentation. Data were statistically analyzed using the chi-square and Mann-Whitney U tests, and P < .05 was set as significant.Results
The success rate for IANBs with an intraligamentary injection was 75%, and for IANBs with a buccal injection, it was 65.6%. For IANBs alone, the success rate was 28.1%.Conclusions
Considering the limitations of the present study, in can be concluded that the success rate of IANBs increased with intraligamentary injections and buccal infiltrations with articaine that were performed before initiating treatment. Also, none of the injection methods showed complete success in anesthesia in all patients. 相似文献2.
Introduction
The aim of this study was to measure the time consumed preparing retrograde cavities in root canals of maxillary molars filled using the GuttaCore (Dentsply Tulsa Dental Specialties, Tulsa, OK) technique and the cold lateral condensation technique (CLC) and to examine the quality of the root-end cavity preparation by ultrasonic tips using micro–computed tomographic (micro-CT) scanning.Methods
A total of 24 maxillary molars were included; distobuccal and palatal canals were instrumented to size #40 and size #50, respectively. Teeth were randomly distributed into 2 experimental groups; half of the samples were filled with CLC, and half were filled with the GuttaCore technique. After 2 months, the apical 3 mm of each root apex was resected. A retrograde cavity was then prepared 3 mm deep into the root-end–filled canals using ultrasonic tips. The quality of the preparation was first confirmed by a surgical stereomicroscope, and the time required for the root-end preparation was recorded. After root-end cavity preparation, all samples were scanned by micro-CT scanning.Results
There was no significant difference between the palatal and distobuccal canals in the time required to prepare a retrograde cavity. Less time was required in the GuttaCore group to remove all root filling material and finish the cavity preparation than in the CLC group (P < .05), especially in the palatal canals. Micro-CT results confirmed that all material was removed from the root-end cavities and the absence of microcracks.Conclusions
GuttaCore was removed in less time from root-end cavities than root filling performed with the CLC technique. No damage to the surrounding dentin was detected by micro-CT scanning in the 2 groups. 相似文献3.
Yemi Kim Byoung-Duck Roh Yooseok Shin Bom Sahn Kim Yoo-lim Choi Aena Ha 《Journal of endodontics》2018,44(1):46-50
Introduction
The aim of this study was to determine the morphologic characteristics of mandibular first molars having 2 canals in distal roots. Interorifice distance, buccal bone thickness, and root curvature were evaluated using cone-beam computed tomography images in a Korean population.Methods
In total, 1958 mandibular first molars were evaluated in axial, coronal, sagittal, and paraxial planes. Distal roots having 2 canals were classified according to their root and canal shapes (2 roots, 2 canals [2R2C]; 1 root, 2 canals with 2 apical foramina [1R2C(2-2)]; and 1 root, 2 canals with 1 apical foramen [1R2C(2-1)]). The distances between orifices and the distance from the apex to the buccal bone plate were measured for each root canal shape (2R2C, 1R2C[2-2], and 1R2C[2-1]). The curvature of distolingual (DL) roots was classified according to severity using 3-dimensional reconstructed images, and the direction of curvature was determined. The relationships of these characteristics to sex and side were evaluated.Results
The prevalences of 2R2C, 1R2C(2-2), and 1R2C(2-1) were 25.89%, 10.32%, and 14.15%, respectively. The distances between distobuccal (DB) and DL orifices were 3.77 ± 0.74 mm for 2R2C, 3.02 ± 0.65 mm for 1R2C(2-2), and 2.44 ± 0.64 mm for 1R2C(2-1). The distances from the buccal plate to the DB canal were 3.84 ± 1.35 mm for 2R2C, 5.33 ± 1.41 mm for 1R2C(2-2), and 5.96 ± 1.63 mm for 1R2C(2-1). The distance from the buccal plate to the DL canal was 9.85 ± 1.46 mm for 2R2C, and 8.28 ± 1.50 mm for 1R2C(2-2). All distances differed significantly according to root canal configurations, and all were greater in men than women (P < .05), except for the DB-DL orifice distance in 1R2C(2-2) and the DB to buccal cortical plate distance in all root configurations (P > .05). No significant difference between the left and right sides was found (P > .05). The prevalence of most severely curved DL roots (type III) was 62.92%, and the direction was commonly toward the buccal side (69.03%).Conclusions
The prevalence of mandibular first molars having 2 canals in distal roots was more than 50% in a Korean population. Interorifice distances between DB and DL canals and distances from the apex to the buccal cortical plate differed according to root and canal numbers and shapes. 相似文献4.
Introduction
The present study aimed to quantitatively analyze apical foramen deviations of mesial root canals of mandibular first molar teeth by means of micro–computed tomographic (micro-CT) imaging.Methods
Micro-CT images of the mesial roots of 109 mandibular first molar teeth with independent mesiobuccal (MB) and mesiolingual (ML) root canals were analyzed. The deviations of the apical foramina of the MB, ML, and middle mesial root canals from the anatomic apex were measured. The vertical distance between the apical foramina of each mesial root canal in relation to each other was also calculated.Results
The distances from the apical foramina of the MB, ML, and middle mesial root canals to the anatomic apex of the mesial root were up to 2.51 mm, 3.21 mm, and 5.67 mm, respectively. There was no significant difference between the deviations of MB and ML root canals from each other (P > .05). The middle mesial root canal showed the greatest deviation compared with the MB and ML canals (P < .05).Conclusions
The apical foramina of mesial root canals of mandibular first molar teeth showed greater variations from each other and anatomic apices than previously reported. Clinically, the use of electronic apex locators for the detection of minor apical foramen of each mesial root canal is of the utmost important. 相似文献5.
Lara Valentina Comini Giuseppe Spinelli Giuditta Mannelli 《Journal of cranio-maxillo-facial surgery》2018,46(12):2127-2137
Purpose
Local flaps are currently considered the main reconstructive option for medium-size oral and peri-oral defects; however, their indications are sometimes challenging to select. The aim of this study was to critically analyse their selection and to propose a therapeutic algorithm.Materials and methods
We performed a search on PubMed regarding the medium-size oral and peri-oral defects reconstruction, and we collected data on the aetiology, the location of the defect, the type of flap used and postoperative complications. The final proposed treatment algorithm was the product of this analysis.Results
We found 111 articles and 2504 flaps (236 buccinator flaps, 60 masseter flaps, 466 facial artery myomucosal flaps, 285 tongue flaps, 95 palatal flap, 525 buccal fat pad flaps and 835 local lip flaps). The most frequent defect localizations included floor of mouth (203 flaps), cheek (242 flaps), anterior hard palate (418 flaps) and upper and lower lip (274 and 559 flaps). Partial flap necrosis and dehiscence occurred in 3% of cases whereas total necrosis in 1%.Conclusions
Local flaps are a good option for oral and perioral defect reconstruction. An appropriate choice of the flap to be used based on the location of the defect is essential for a correct reconstruction. 相似文献6.
Carlos Estrela Gabriela Soares Couto Mike R. Bueno Kelvin G. Bueno Lucas R.A. Estrela Olavo César Lyra Porto Anibal Diogenes 《Journal of endodontics》2018,44(11):1741-1748
Introduction
The purpose of this study was to determine the position of the apical foramen (AF) in relation to root surfaces of human permanent teeth using cone-beam computed tomographic (CBCT) imaging and novel advanced imaging analysis software (e-Vol DX; CDT Software, Bauru, SP, Brazil).Methods
The AF position was determined on CBCT scans viewed and analyzed using e-Vol DX of 1400 teeth (422 patients) according to the root surface as follows: buccal, mesiobuccal, mesial, mesiolingual/palatal, lingual/palatal, distolingual/palatal, distal, distobuccal, and central. Categoric variables were described as frequencies and percentages. Frequencies were reported with their confidence intervals (95%). Categoric variables were analyzed using the chi-square test with Yates correction. The level of significance was set at α = 0.05.Results
The most frequent AF position in maxillary anterior teeth was central (46%–60%). The AF in mandibular central incisors was buccal in 44% of the cases. In maxillary first and second premolars, 39.98% and 42.56% of all AFs were central. In maxillary first and second molars, 46.12% and 57.49% of all AFs were central. The most frequent AF position in mandibular first and second premolars was central (42.85% and 50.98%). In mandibular first molars, 48.72% of all AFs were central.Conclusions
The AF position in human permanent teeth was central in 48.95% and 42.08% of the maxillary and mandibular teeth. CBCT images analyzed by e-Vol DX can be used to determine the true anatomic position of the AF and can be a useful tool for the treatment planning of nonsurgical and surgical endodontic treatments. 相似文献7.
Ben Studebaker Lars Hollender Lloyd Mancl James D. Johnson Avina Paranjpe 《Journal of endodontics》2018,44(4):565-570
Introduction
Many endodontic treatment failures in maxillary molars result from missed second mesiobuccal (MB2) canals. An MB2 canal orifice is present in as many as 95% of maxillary molars, but these canals are not always located during endodontic procedures. Additional tools, such as cone-beam computed tomographic (CBCT) imaging, may be needed to locate these canals in maxillary molars. Hence, the aims of this study were to investigate the frequency of use of CBCT imaging during the treatment of maxillary molars and to evaluate the influence of its use on the detection of MB2 canals.Methods
Endodontic treatment records, digital intraoral radiographs (when present), and CBCT images from all maxillary first and second?molars treated at the University of Washington, Seattle, WA, between 2010 and 2014 (N?=?886) were reviewed. Statistical analysis was performed to assess differences between the groups.Results
Overall, an MB2 canal was found in 55.8% of the maxillary molars studied, and CBCT imaging assisted in detecting 11.7% of these canals. CBCT imaging was used in 16.5% of the cases treated and was used significantly more for retreatment cases. CBCT imaging was used preoperatively in 5.6% of cases, and the data show that significantly more MB2 canals were located when a preoperative CBCT image was available. More MB2 canals were located in first molars without full-coverage crowns.Conclusions
The data show that CBCT imaging is a valuable tool in locating MB2 canals. Based on the results of his study, the use of CBCT imaging could be warranted when treating maxillary molars. 相似文献8.
Introduction
The present study aimed to anatomically assess mandibular posterior teeth using cone-beam computed tomographic (CBCT) imaging for endodontic surgery.Methods
A total of 170 CBCT scans were evaluated for anatomic variations of mandibular posterior teeth. All the scans were obtained using a Planmeca Promax CBCT unit (Planmeca, Helsinki, Finland) with exposure settings of 90 kVp, 12 mA, 12 seconds, and 0.3-mm resolution. All CBCT images were reconstructed by Romexis Viewer 3.8.2. software (Planmeca) on a 16-inch LCD monitor (22MP47HQ; LG, Seoul, South Korea), and axial, coronal and sagittal views were evaluated.Results
The thickest buccal cortical plate was observed over the distal root of second molars (12.30 mm) among the molar teeth and over the second premolar root (5.41 mm) among the premolar teeth. The thinnest buccal cortical plate was observed over both the first and second premolar roots (0.42 mm) and over the mesial root of the first molar (0.62 mm) tooth. A 20.38-mm section was removed for surgical access during buccal resection of the distal root of the left second molar, and the closest distance from the apex to the inferior alveolar canal was 0 mm.Conclusions
Adequate knowledge of the anatomic dimensions of teeth and their surrounding structures is imperative for endodontic surgery. Information concerning the root thickness of mandibular posterior teeth at the site of root resection (apical 3 mm), buccal cortical plate thickness, and the distance from the apex of each tooth to the inferior alveolar canal and mental foramen can guide the surgeon before and during surgery. 相似文献9.
Masoud Saatchi Maryam Shafiee Abbasali Khademi Bahareh Memarzadeh 《Journal of endodontics》2018,44(3):384-388
Introduction
The purpose of this prospective, randomized clinical trial was to evaluate the anesthetic efficacy of the Gow-Gates nerve block (GGNB), the inferior alveolar nerve block (IANB), and their combination for mandibular molars in patients with symptomatic irreversible pulpitis.Methods
One hundred fifty patients diagnosed with symptomatic irreversible pulpitis of a mandibular molar were selected. The patients randomly received 2 GGNB injections, 2 IANB injections, or 1 GGNB injection plus 1 IANB injection of 1.8 mL 2% lidocaine with 1:80,000 epinephrine. Access cavity preparation was initiated 15 minutes after injections. Lip numbness was a requisite for all of the patients. Success was specified as no or mild pain on the basis of Heft-Parker visual analog scale recordings during access cavity preparation or initial instrumentation. Data were analyzed with the chi-square, Kruskal-Wallis, and analysis of variance tests.Results
The success rates of anesthesia were 40%, 44%, and 70% for the GGNB, IANB, and GGNB + IANB groups, respectively. There was no statistically significant difference in the success rate of anesthesia between the GGNB and IANB groups (P > .05). The anesthesia success rate for the GGNB + IANB group was significantly different from those of the GGNB and IANB groups (P < .05).Conclusions
A combination of GGNB and IANB could improve the efficacy of anesthesia in mandibular molars with symptomatic irreversible pulpitis, but it would still require supplemental anesthesia. Further research may be needed to confirm the results of this study. 相似文献10.
Konstantinos Natsis Maria Piagkou Nikolaos Lazaridis Trifon Totlis Nikolaos Anastasopoulos Jannis Constantinidis 《Journal of cranio-maxillo-facial surgery》2018,46(4):635-644
Purpose
The current study investigated the incidence, morphology and morphometry of the ossified ligaments expanding between petrous bone and posterior clinoid processes and in between the anterior, middle and posterior clinoid processes. Side symmetry, gender dimorphism and age influence were also studied.Materials and Methods
A total of 123 adult Greek dry skulls were observed.Results
A caroticoclinoid bar (CCB) was found in 60.2%. Partial CCBs appeared more commonly (36.6%) than complete (23.6%). The caroticoclinoid foramen (CCF) was symmetrical on both sides and genders. An anterior interclinoid, a posterior petroclinoid and a partial posterior interclinoid bar appeared in 19.5%, 6.5% and 2.4%, respectively. Osseous spurs posterolateral to the posterior clinoid process were present in 5.7%.Conclusion
The study highlights important morphometric details about osseous bars of the sella region and the related CCF in Greek skulls. Notable differences in the incidence of these bars in Greek individuals compared with findings from other populations highlight the growing awareness of ethnic differences in skull base landmarks. Variations and surgically oriented measurements provided by this study may benefit clinicians involved in the treatment of the middle cranial fossa pathology, enriching understanding of the complicated regional anatomy. Preoperative sellar area mapping is essential, by using computed tomography images, since modification of the surgical approach may be required in cases of severe ossification. 相似文献11.
Introduction
The purpose of this study was to assess temperature development in endodontic sealers during different obturation techniques in a closed system simulating the surrounding biological structures at body temperature.Methods
The root canals of 48 human single-rooted maxillary canines were instrumented with ProTaper Gold (Dentsply Sirona, York, PA) to size F3. On the buccal aspect of each root, artificial side canals with a diameter of 0.5 mm were drilled at a distance of 3, 6, and 9 mm from the apical foramen, and type K thermocouples were inserted via plastic pipes. The roots were positioned in plastic vials filled with alginate. The root canals were obturated by the continuous wave and warm backfill technique, Thermafil obturators (Dentsply Sirona), or single-cone obturation (n = 12) at body temperature using AH Plus sealer (Dentsply Sirona). Temperature measurement during the obturation procedure was assessed by thermocouples. Statistical analysis of the maximum temperature change was performed using the Kruskal-Wallis test (P = .05).Results
The continuous wave and warm backfill technique caused significantly higher temperatures than Thermafil and single-cone obturation (P < .05). The continuous wave technique revealed significantly higher temperatures than the warm backfill technique at 3 mm and 6 mm from the apex (P < .05).Conclusions
In a closed system with simulated surrounding tissues at 37°C, the continuous wave technique produced higher increases in temperature than the warm backfill technique with a maximum of 19.1°C. The temperature increase during Thermafil obturation was negligible. The temperature increase in the endodontic sealer was markedly lower than expected from root surface temperature measurement studies. 相似文献12.
Felipe Gonçalves Belladonna Marco Simões Carvalho Daniele Moreira Cavalcante Jaqueline Tavares Fernandes Ana Carolina de Carvalho Maciel Henrique Eduardo Oliveira Ricardo Tadeu Lopes Emmanuel João Nogueira Leal Silva Gustavo De-Deus 《Journal of endodontics》2018,44(7):1146-1150
Introduction
The present study aimed to assess canal preparation outcomes achieved by the new Reciproc Blue instrument using micro–computed tomography technology. M-Wire Reciproc was used as a reference instrument for comparison.Methods
Seven pair-matched mesial roots of mandibular molars presenting similar anatomic features of the canal (length, volume, surface area, and configuration) were selected after scanning procedures and assigned to 1 of the 2 groups according to the instrument used, M-Wire Reciproc and Reciproc Blue. After canal instrumentation, the specimens were rescanned, and the registered preoperative and postoperative datasets were examined to evaluate the percentages of removed dentin, untouched canal walls, and degree of canal transportation. Comparisons regarding the above outcomes between the 2 groups were done by using paired t test with the alpha-type set at 5%.Results
Root canals prepared with conventional M-Wire Reciproc or Reciproc Blue were found to present similar shaping properties with no significant differences in the tested parameters.Conclusions
M-Wire Reciproc and Blue Reciproc presented similar shaping outcomes. 相似文献13.
Sy Yin Chai Vincent Bennani John M. Aarts Karl Lyons 《Journal of the American Dental Association (1939)》2018,149(1):25-37
Background
The authors reviewed and identified the evidence for the various incisal preparation designs for ceramic veneers.Types of Studies Reviewed
The authors searched MEDLINE with PubMed and Ovid to identify any articles in the English language related to the topic up through March 2017 using a combination of key words: “porcelain veneer or ceramic veneer or dental veneer or labial veneer” AND “preparation,” NOT “composite veneer,” NOT “crown,” NOT “implant,” NOT “fixed partial denture or bridge or denture,” NOT “porcelain-fused-to-metal,” NOT “marginal gap or fit.”Results
In vitro studies showed that the palatal chamfer preparation design increases the risk of developing ceramic fractures. The butt joint preparation design had the least effect on the strength of the tooth.Conclusions
Surveys show the 2 most common incisal preparation designs provided are butt joint and feathered-edge. Clinical studies have identified that incisal ceramic is the most common location of ceramic fracture. In addition, there is a lack in standardization of the modeling structures and type of finite element analysis.Practical Implications
The evidence seems to support the use of butt joint over palatal chamfer incisal preparation design. Fracture or chipping is the most frequent complication and the risk increases with time. Incisal ceramic is the most common location of ceramic fracture. 相似文献14.
Michael R. Shapiro Neville J. McDonald Richard J. Gardner Mathilde C. Peters Tatiana M. Botero 《Journal of endodontics》2018,44(4):523-528
Introduction
Profound pulpal anesthesia is difficult to achieve in mandibular molars with irreversible pulpitis (IP). However, there are no published randomized controlled clinical trials comparing the success of supplemental buccal infiltration (BI) in mandibular first versus second molars with IP. The purpose of this prospective, randomized, double-blind study was to compare the efficacy of 4% articaine with 2% lidocaine for supplemental BIs in mandibular first versus second molars with IP after a failed inferior alveolar nerve block (IANB). This study's sample was combined with data from a previous trial.Methods
One hundred ninety-nine emergency subjects diagnosed with IP of a mandibular molar were selected and received an IANB with 4% articaine. Subjects who failed to achieve profound pulpal anesthesia, determined by a positive response to cold or pain upon access, randomly received 4% articaine or 2% lidocaine as a supplemental BI. Endodontic access was begun 5 minutes after infiltration. Success was defined as less than mild pain during endodontic access and instrumentation on the Heft-Parker visual analog scale.Results
There was a 25% IANB success rate with 4% articaine. The success rate for articaine supplemental BI in first molars was 61% versus 63% for second molars (P > .05). The success of lidocaine in first molars was 66%, but for second molars it was 32% (P = .004).Conclusions
The success rate for IANB with 4% articaine was 25%. Articaine and lidocaine had similar success rates for supplemental infiltration in first molars, whereas articaine was significantly more successful for second molars. However, because BI often did not provide profound pulpal anesthesia, additional techniques including intraosseous anesthesia may still be required. 相似文献15.
Introduction
Maxillary premolars are among the teeth most susceptible to vertical root fracture (VRF) from lateral condensation of gutta-percha. These teeth are distinguished by a complex anatomy of the buccal root including a large depression in the dentin wall facing the bifurcation. It is hypothesized that tooth sectioning coupled with 2-dimensional fracture analysis is instrumental in understanding VRF in such teeth. VRF was examined by tooth sectioning following the development of a fracture mechanics analysis to predict VRF in such roots.Methods
The fracture morphology in teeth extracted from patients because of VRFs was examined from a series of horizontal cross sections. 2-dimensional fracture mechanics analysis in conjunction with the finite element technique was developed to evaluate VRF caused by canal pressure (q). As in our previous single-rooted tooth model, the apical obturation force (F) was related to q using a simple formula.Results
Fracture was mostly limited to the buccal root, exhibiting some competing modes including fracture from the depression peak to the canal surface and the canal surface to the root surface, which may occur either along straight lines or curved trajectories resembling the depression outline. The analysis predicted clinical fractures well, yielding VRF force values in the upper range used by clinicians during lateral condensation of gutta-percha.Conclusions
The main etiology for VRF is stress concentration resulting from the combined effect of wedgelike canal depression and the flexibility of periodontal ligament tissue joining the root and bone. This drawback can be alleviated by minimizing canal enlargement and apical condensation force during root canal therapy. 相似文献16.
Introduction
The aim of this study was to evaluate the effect of supplementary use of XP-endo Finisher file, passive ultrasonic activation (PUI), EndoActivator (EA), and CanalBrush (CB) on the removal of calcium hydroxide (CH) paste from simulated internal resorption cavities.Methods
The root canals of 110 extracted single-rooted teeth with straight canals were prepared up to size 50. The specimens were split longitudinally, and standardized internal resorption cavities were prepared with burs. The cavities and root canals were filled with CH paste. The specimens were divided into 5 groups as follows: XP-endo Finisher, EA, PUI, CB, and syringe irrigation (SI). The root canals were irrigated with 5.25% NaOCl and 17% EDTA for 2 minutes, respectively. Apart from the SI group, both solutions were activated by using tested techniques for 1 minute. The quantity of CH remnants on resorption cavities was scored. Data were analyzed by using Kruskal-Wallis H and Mann-Whitney U tests.Results
XP-endo Finisher and PUI removed significantly more CH than SI, EA, and CB (P < .05), showing no significant difference between them (P > .05). Differences among SI, EA, and CB were also non-significant (P > .05).Conclusions
None of the tested techniques render the simulated internal resorption cavities free of CH debris. XP-endo Finisher and PUI were superior to SI, CB, and EA. 相似文献17.
Sabrina C. Brasil Marília F. Marceliano-Alves Márcia L. Marques João P. Grillo Mariane F.L.S. Lacerda Flávio R.F. Alves José F. Siqueira José C. Provenzano 《Journal of endodontics》2017,43(10):1683-1687
Introduction
This study compared the shaping ability of ProTaper Next (Dentsply Sirona, Tulsa, OK) and BT-RaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland) instrument systems in the mesial canals of mandibular molars using micro–computed tomographic (micro-CT) imaging.Methods
A total of 17 type IV mesial roots of extracted first mandibular molars were scanned using micro-CT imaging before and after root canal preparation with the 2 instrument systems. Both systems were used in the same root but alternating the mesial canals from root to root. The following parameters were analyzed: root canal volume, surface area, unprepared surface areas, transportation, canal/root width ratio, and preparation time.Results
There were no statistically significant differences between the 2 systems for all evaluated parameters (P > .05). The unprepared surface areas for the full canal length and the apical 5-mm segment were 33% and 14% for BT-RaCe and 31% and 14% for ProTaper Next, respectively. After preparation, all root canals had a diameter that was not larger than 35% of the root diameter at the coronal and middle segments.Conclusions
The 2 systems showed no differences in any of the evaluated shaping parameters. None of the tested systems put the roots at risk of fracture because of excessive dentin removal. 相似文献18.
Introduction
Recently, different rotary glide path systems have been introduced. The aim of this study was to compare the centering ability of different rotary pathfinding systems and their effect on the final preparation by Hyflex CM files.Methods
Sixty endodontic training blocks with J-shaped canals were divided into 3 groups according to the pathfinding system used. Instrumentation was done with G-File + Hyflex CM (G-File group), PathFile + Hyflex CM (PathFile group), and Hyflex GPF + Hyflex CM (GPF group). Three images were taken: initial, after glide path preparation, and after final instrumentation. Pre-instrumentation and post-instrumentation images were superimposed, and centering ratio along the J-shaped canal was measured to evaluate the occurrence of deviation. Statistical analysis of the data was performed by using one-way analysis of variance, followed by Tukey test (α = 0.05).Results
The ability of instruments to remain centered in canals at 0-mm level (apex) was significantly lower in PathFile group (P < .05). No significant difference was found at other levels. After final preparation by Hyflex CM no significant difference was found at any level.Conclusions
The centering abilities of Hyflex GPF and G-Files are better than that of PathFile at apex, but it has no significant effect on final preparation by Hyflex CM. 相似文献19.
David Lalande Jeffrey A. Hodd John S. Brousseau Van Ramos Daniel Dunham Frederick Rueggeberg 《The Journal of prosthetic dentistry》2018,119(6):948-953
Statement of problem
Because crowns with open margins are a well-known problem and can lead to complications, it is important to assess the accuracy of margins resulting from the use of a new technique. Currently, data regarding the marginal fit of computer-aided design and computer-aided manufacturing (CAD-CAM) technology to fabricate a complete gold crown (CGC) from a castable acrylate resin polymer block are lacking.Purpose
The purpose of this in vitro study was to compare marginal discrepancy widths of CGCs fabricated by using either conventional hand waxing or acrylate resin polymer blocks generated by using CAD-CAM technology.Material and methods
A plastic model of a first mandibular molar was prepared by using a 1-mm, rounded chamfer margin on the entire circumference of the tooth. The master die was duplicated 30 times, and 15 wax patterns were fabricated by using a manual waxing technique, and 15 were fabricated by using CAD-CAM technology. All patterns were invested and cast, and resulting CGCs were cemented on their respective die by using resin-modified glass ionomer cement. The specimens were then embedded in acrylic resin and sectioned buccolingually. The buccal and lingual marginal discrepancies of each sectioned portion were measured by using microscopy at ×50 magnification. Data were subjected to repeated measures 2-way ANOVA, by using the Tukey post hoc pairwise comparison test (α=.05).Results
The factor of “technique” had no significant influence on marginal discrepancy measurement (P=.431), but a significant effect of “margin location” (P=.019) was noted. The confounding combination of factors was found to be significantly lower marginal discrepancy dimensions of the lingual margin discrepancy than on the buccal side by using CAD-CAM technology.Conclusions
The marginal discrepancy of CAD-CAM acrylate resin crowns was not significantly different from those made with a conventional manual method; however, lingual margin discrepancies present from CAD-CAM–prepared crowns were significantly less than those measured on the respective buccal surface. 相似文献20.
Melissa Drum Al Reader John Nusstein Sara Fowler 《Journal of the American Dental Association (1939)》2017,148(4):267-271